Derive me maybe?
by Schwester Aurelia
Summary: Rodney gets an unexpected little show when he comes home. Happy, fluffy fic with singing, and maths. :) Enjoy!


**Derive Me Maybe?**

 _Hi everyone!_

 _I had so much fun with "Finite simple group of order two" that I decided to do another math song fic. :D_

 _Caution! There are spoilers ahead! Skip to the end notes for more information, or just read on for a surprise! (It's nothing bad, just further developments that happen some time after "In a better future")_

* * *

Rodney comes home to the sound of singing. Slightly off-key, but very enthusiastic singing.

He pauses in the doorway to their living room. He watches with a fond smile how Nemia hops around excitedly in rhythm with the music, singing along with John.

John sits on the sofa, strumming his guitar, his voice the bass to Nemmy's soprano.

It seems to be one of that pop songs that were super popular on Earth a few years back – but with a slightly different text than Rodney remembers.

He just enjoys the show his family is making.

When the song ends, Nemmy runs to John for a hug, and claps her hands in delight. "Again! Again please, daddy!"

John gives her a hug, and a kiss, and then gestures to Rodney with a grin. "You wanna say hi to your pa first?"

Nemia whirls around, and her eyes light up when she spots Rodney by the door. Rodney can't help but grin in return when she barrels into him full force with a squeal of joy.

He throws her in the air, and catches her again. "Hey Nemmy. Having a good day?"

She nods solemnly, while Rodney walks the few steps to the sofa, and sits down next to John with her in his lap.

"Yes, I do! Lantis taught me this really funny song, and then I asked daddy if he can play it, and he can!"

Rodney chuckles. "I heard. Your daddy is a very talented man."

John gives his husband a wink, and leans in for a kiss. "Thanks, dear. Wanna hear the whole thing?"

"Sure!"

Nemia jumps up from Rodney's lap immediately, taking position in front of her fathers.

John starts to play, and they sing together, Nemmy dancing around again with abandon.

 _ **1)**_

 _I made a wish about you, x of t is 22,_

 _I looked to you for a clue, v of t decreasing._

 _I'd make the graph concave up, the integral I'd set up,_

 _Rotate it into a cup, radius increasing._

 _ **Pre-Chorus**_

 _Study the relation, trying integration,_

 _Graph the correlation, why'd you use u-substitution?_

 _ **Chorus**_

 _Hey! I just met you, and this is crazy,_

 _But here's my du, derive me maybe?_

 _It's hard to integrate without you baby_

 _But here's my du, derive me maybe?_

 _Hey! I just met you, and this is crazy,_

 _But here's my du, derive me maybe?_

 _And all the secants intersect me,_

 _But here's my du, derive me maybe?_

 _ **2)**_

 _I took the range and domain, you found that it was no pain,_

 _Limits all over the plane, you made them undefined._

 _Can't find your min or your max, you just stopped dead in your tracks,_

 _Gotta remember the facts to see the graph's design._

 _ **Pre-Chorus + Chorus**  
_

 _ **Bridge**_

 _Before I learned l'Hopital's rule, limits were so bad,_

 _Limits were so bad, limits were so so bad._

 _Before I learned l'Hopital's rule, limits were so bad,_

 _I know too well that, limits were so so bad._

 _ **Chorus**_

 _ **Bridge**_

Rodney has to snort at some points, it's just too funny.

At the end of the song, Nemia throws herself into Rodney's arms again. He gladly hugs her, and lets her settle into his lap.

"That was really good, honey. Thank you for showing me."

"Pa? What does it mean?"

It's John's turn to snort now, and he gets up to put his guitar back into its stand.

"Oh this is gonna be good."

Rodney narrows his eyes at his husband. Sure – Nemmy is only 5, but that's no reason not to start with the basics of differentiation, especially since she _asked_.

He grabs the nearest tablet from the coffee table, quickly drawing a few graph. John sits down again next to them, and throws a casual arm around Rodney's shoulder.

"Okay, see this? This is called the graph of a function. It can move in lots of different ways. See, it can go in a straight line... or in a curve... or go up and then down again..."

He sketches a few graphs, and Nemmy listens intensely, nodding in understanding.

"Now, sometimes you wanna draw a straight line into that graph, that shows exactly how much it goes up or down at the moment."

He adds a few secants and tangents to the graphs.

"Why?"

John chuckles, and Rodney gives him a quelling look.

"You use those to calculate lots of different things, for example how a Jumper moves through the air."

Nemmy's eyes go wide. "Really?!"

Rodney smiles. "Yeah. I can show you the graphs next time we take a trip. Now, sometimes it's quite easy to find the right angle, like when the function is just a straight line. But it gets harder the more complex the function is. There is a operation called differentiation that helps with that. You find the derivative of the function. That's what the lyrics are about: Derive me maybe."

"Okay! Can you draw more funny lines, pa?"

Rodney sees that her interest in the mathematical background is sated for now, and gamely obliges.

He gives John a smug smile over her head while she has fun drawing her own graphs.

John rolls his eyes fondly, but leans in for another kiss, whispering "Dork".

Rodney narrows his eyes at that flyboy. Oh, it is _on_. Tonight, when Nemmy is in bed, John is so gonna pay for that.

The grin John gives him says clearly he has a good idea what is coming his way, and can hardly wait.

* * *

 _Hehehehe._

 _Rodney lives by the principle that there are no unsuitable topics for children. If they're old enough to ask, they're old enough to get an explanation. Adjusted to their level of understanding of course, but you have to do that with grad students too, so..._

 _This song is, of course, a parody of "Call me maybe?" and you can watch a brilliant video of it when you search youtube for "Derive me maybe"!_

 _Little background info / **SPOILERS!**_

 _John found Nemmy three years ago while they were on a rescue mission. A village had been attacked by the Wraith, and Atlantis lent troops for help. John was just in time to stop a Wraith from feeding on the little girl, and then carried her to safety. She didn't want to let go of him, and her parents had been killed by the Wraith._

 _So he took her home – and later adopted her together with Rodney._

 _There is gonna be a whole story about how that happened, sometime... later._

 _I hope you had fun, I certainly did! (There are so many brilliant math songs I just might do another one one day... Or another songfic, suggestions are always welcome!)_

 _Have a nice day! ^_^_


End file.
